feat: allow install command's version parameter to be evaluated (#102)

* feat: allow evaluation of `version` param

This will allow support of users passing in env vars, like `'${MY_RUBY_VERSION}'` or things like `'$(cat foo/bar/.ruby-version)'`.

* chore: modify integration-test CI job to use Ruby 2.7.5 as per demo rails project

* docs: update description for commands.install.parameters.version.description

* test: add additional test for installing Ruby version specified in env var

.circleci/test-deploy.yml

@@ -19,7 +19,10 @@ executors:
 jobs:
   integration-tests:
     docker:
-      - image: cimg/ruby:2.7-node
+      # NOTE: the specific Ruby version required is based on https://github.com/CircleCI-Public/circleci-demo-ruby-rails
+      # See https://github.com/CircleCI-Public/circleci-demo-ruby-rails/blob/2033c5f8da3010941127e0f9133925bd8efc7a79/Gemfile#L10
+      # When the project's Ruby version requirement is updated, we will need to update here as well.
+      - image: cimg/ruby:2.7.5-node
       - image: cimg/postgres:14.2
         environment:
           POSTGRES_USER: circleci-demo-ruby
@@ -70,7 +73,7 @@ jobs:
   install-on-machine:
     parameters:
       image:
-        description: Enter the version that should be user for the machine executor.
+        description: Enter the version that should be used for the machine executor.
         type: string  
     executor: 
       name: ubuntu
@@ -90,6 +93,19 @@ jobs:
         - run:
             name: "Test Install"
             command: ruby --version | grep "2.6"
+  install-from-env-var:
+      docker:
+        - image: cimg/node:current
+      steps:
+        - run:
+            name: Set RUBY_VERSION env var
+            command: |
+              echo "export RUBY_VERSION='2.7.0'" >> $BASH_ENV
+        - ruby/install:
+            version: "${RUBY_VERSION}"
+        - run:
+            name: "Test Install"
+            command: ruby --version | grep "2.7.0"
 
 workflows:
   test-deploy:
@@ -104,6 +120,8 @@ workflows:
           filters: *filters
       - install-on-node:
           filters: *filters
+      - install-from-env-var:
+          filters: *filters
       - orb-tools/pack:
           filters: *filters
       - orb-tools/publish:
@@ -115,6 +133,7 @@ workflows:
             - integration-tests
             - install-on-machine
             - install-on-node
+            - install-from-env-var
           context: orb-publishing
           filters:
             branches:

src/commands/install.yml

@@ -1,7 +1,11 @@
 description: "Install Ruby within a build. To be used in a Linux distro with Apt available."
 parameters:
   version:
-    description: "Ruby version."
+    description: >
+      Ruby version.
+      This can be a literal value (e.g, `2.7.5`).
+      You can also pass in a string to be evaluated.
+      For example, `${MY_RUBY_VERSION}` or `$(cat foo/bar/.ruby-version)`.
     type: string
 steps:
   - run:

src/scripts/install-ruby.sh

@@ -1,7 +1,9 @@
 #!/usr/bin/env bash
 
-rvm install "$PARAM_VERSION"
-rvm use "$PARAM_VERSION"
+PARAM_RUBY_VERSION=$(eval echo "${PARAM_VERSION}")
 
-readonly ruby_path="$(rvm $PARAM_VERSION 1> /dev/null 2> /dev/null && rvm env --path)"
-printf '%s\n' "source $ruby_path" >> $BASH_ENV
+rvm install "$PARAM_RUBY_VERSION"
+rvm use "$PARAM_RUBY_VERSION"
+
+readonly ruby_path="$(rvm $PARAM_RUBY_VERSION 1> /dev/null 2> /dev/null && rvm env --path)"
+printf '%s\n' "source $ruby_path" >> $BASH_ENV